Heat conduction and friction manometers or gauges, as well as ioninization manometers or gauges, are used for measuring the total pressure in a low pressure range. Quartz manometers or gauges, which are a species of gas friction manometers or gauges have also been used.
All indirect measuring processes are dependent on the type of the gas, the pressure of which is to be determined. The gas friction process, like all indirect measuring processes, depends on the type of molecule in the environment of the environment, that is, its influence on the sensor, and changes as the molecule changes. Likewise, measuring processes using the heat conduction measuring process depend on the type of molecule in the environment of the measurement, that is, the influence zone of the sensor, and changes as the molecules change.